Electrosurgical lesion location device

ABSTRACT

A device for localizing a target tissue mass in a body includes a tubular trocar portion having a distal end and a proximal end portion that is removably attachable to a handle portion. The trocar portion contains at least a first plurality of locator wires that are movable between a retracted position within the trocar and a deployed position extending radially from the trocar. In a preferred embodiment, the trocar portion has an electrosurgical cutting element at its distal end, and first and second pluralities of locator wires that, when deployed, respectively define first and second locating perimeters. The first plurality of locator wires is connected to a first wire-carrying member longitudinally mounted for axial movement within the trocar portion between a proximal position corresponding to the retracted position of the first plurality of locator wires, and a distal position corresponding to the deployed position of the first plurality of locator wires. The second plurality of locator wires is connected to a second wire-carrying member longitudinally mounted in the trocar portion, coaxially with the first tubular member, for movement between a distal position corresponding to the retracted position of the second plurality of locator wires, and a proximal position corresponding to the deployed position of the second plurality of locator wires. The trocar portion has an intermediate portion having first and second pluralities of slot-shaped apertures through which the first and second pluralities of locator wires emerge when moved to their respective deployed positions. With the locator wires in their retracted position, the trocar is passed through a target tissue mass until the intermediate portion is within the mass. The locator wires are then deployed within the mass to anchor the trocar therein and to mark the site for a surgical procedure. In the preferred embodiment, the locator wires are electrically energized to facilitate their deployment electrosurgically.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] Not Applicable

FEDERALLY-FUNDED RESEARCH OR DEVELOPMENT

[0002] Not Applicable

BACKGROUND OF THE INVENTION

[0003] The present invention relates generally to the field ofelectrosurgical instruments. More specifically, it relates to a devicethat electrosurgically fixes and identifies the location, in situ, of apathologically suspect tissue mass in a patient's body, for facilitatingthe accurate surgical removal of the mass.

[0004] It is often medically desirable to remove a pathologicallysuspect tissue mass, such as a suspected tumor or lesion, from apatient's body. For example, in treating breast cancer, a suspicioustissue mass is typically identified and localized by imaging means, suchas mammography or ultrasound. Once localized, the mass is typicallysubjected to a biopsy to determine whether or not it is malignant.Often, the biopsy will be an “open” biopsy, in which all or part of theidentified mass is surgically removed, sometimes with a surroundingmargin of tissue.

[0005] The identification and localization of the suspect mass isusually performed by a radiologist. The patient is then typicallytransported to an operating room for surgery. To allow the surgeon to beable to locate the identified mass, the radiologist places one or morelocalization wires or “Kopan's” wires into the breast to define andlocate the tissue mass to be removed. In using a localization wire, ahollow needle or cannula, containing the localization wire, is insertedinto the breast under local anaesthesia, while the breast is undercompression during the imaging procedure, until the distal end of thelocalization wire passes through the suspect mass. The localization wireis anchored distally beyond the mass by means such as a barb or hook atthe distal end of the wire. The cannula is then removed from the body,leaving the wire in place and extending from the body as a marker forthe surgeon.

[0006] The above-described procedure has certain shortcomings, however.One problem stems from the fact that the localization wire is insertedwhile the breast is under compression during mammography. When thebreast is released from compression, the distal end of the wire oftenmigrates and thus shifts position with respect to the targeted tissuemass. This may lead to inaccurate placement of the incision for thebiopsy, with the result that either an excess of tissue outside of thetarget tissue mass is removed, or less than all of the target tissuemass is removed. In addition, the wire is sometimes inadvertentlyshifted, severed, or pulled out during surgery, thereby defeating itspurpose of accurately guiding the surgeon to the target tissue mass. Anyinaccuracies in guiding the surgeon can result in larger than necessaryamounts of healthy tissue being removed, with resultant deformation andscarring of the breast, or in the need to re-enter the incision site toremove parts of the target tissue mass that were missed on the firstbiopsy attempt.

[0007] Another shortcoming associated with prior art localizationdevices is that, while the location of the target tissue mass can bemarked, no indication is provided of the dimensions of the mass. Thus,accurate removal of the desired amount of tissue depends on thesurgeon's ability to determine the boundaries of the tissue mass duringsurgery.

[0008] It would therefore be advantageous to provide a localizationdevice that minimizes or eliminates the aforementioned problemsassociated with the migration and inadvertent removal of thelocalization wire. It would be further advantageous for such a device toprovide an accurate indication of the dimensions and boundaries of thetarget tissue mass. Furthermore, such a device should be easy to use,and should be compatible with existing imaging equipment and surgicalmethods.

SUMMARY OF THE INVENTION

[0009] Broadly, the present invention is a device for localizing atarget tissue mass in a body, comprising a tubular trocar with at leasta first plurality of locator wires that are movable between a retractedposition fully contained within the trocar and a deployed positionextending radially from the trocar. In a preferred embodiment, thedevice includes an electrosurgical cutting element at its distal end,and first and second pluralities of locator wires that, when deployed,respectively define first and second locating perimeters. The firstplurality of locator wires is connected to a first tubular wire-carryingmember longitudinally mounted for axial movement within the trocarbetween a proximal position corresponding to the retracted position ofthe first plurality of locator wires, and a distal positioncorresponding to the deployed position of the first plurality of locatorwires. The second plurality of locator wires is connected to a secondtubular wire-carrying member longitudinally mounted in the trocar,coaxially with the first tubular member, for movement between a distalposition corresponding to the retracted position of the second pluralityof locator wires, and a proximal position corresponding to the deployedposition of the second plurality of locator wires. The trocar has aportion having first and second pluralities of slot-shaped aperturesthrough which the first and second pluralities of locator wires emergewhen moved to their respective deployed positions.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a perspective view of an electrosurgical deviceconstructed in accordance with the present invention;

[0011]FIG. 2 is a perspective view of the distal end of the tubulartrocar of the device illustrated in FIG. 1;

[0012]FIG. 3 is a longitudinal cross-sectional view of the tubulartrocar, taken along line 3-3 of FIG. 2, showing the locator wires intheir retracted position;

[0013]FIG. 4 is a cross-sectional view taken along line 3-3 of FIG. 2,but with the tubular members of the trocar arranged to partially deploythe locator wires;

[0014]FIG. 5 is a transverse cross-sectional view of the trocar, takenalong line 5-5 of FIG. 3;

[0015]FIG. 5A is a transverse cross-sectional view of the trocar, takenalong line 5A-5A of FIG. 3;

[0016]FIG. 6 is a transverse cross-sectional view of the trocar, takenalong line 6-6 of FIG. 3;

[0017]FIG. 6A is a transverse cross-sectional view of the trocar, takenalong line 6A-6A of FIG. 3;

[0018]FIG. 7 is a top view, partially in cross-section, of the handleportion of the device illustrated in FIG. 1;

[0019]FIG. 8 is a view of the interior of the handle portion of thedevice illustrated in FIG. 1, with the outer shell of the handle portionremoved, showing the mechanism arranged for the locator wires of thedevice to be in their retracted position;

[0020]FIG. 9 is a view similar to that of FIG. 8, showing the mechanismarranged for the locator wires of the device to be in their deployedposition;

[0021]FIG. 10 is a perspective view of the distal portion of the trocarof the device, with the locator wires in their deployed position;

[0022]FIG. 11 is a side elevational view of the distal portion of thetrocar of the device, with the locator wires in their deployed position;

[0023]FIG. 12 is a side elevational view of a part of the handle portionof the device, with the trocar removed;

[0024]FIG. 13 is a perspective view of the attachment fitting by whichthe trocar of the device is removably attached to the handle portion;

[0025]FIG. 14 is a cross-sectional of a modified form of a locator wirethat may be used in the present invention;

[0026]FIG. 15 is a cross-sectional of another modified form of a locatorwire that may be used in the present invention; and

[0027]FIGS. 16 and 17 are cross-sectional views of a part of the handleportion of the present invention, showing the electrical switchingmechanism and the locking mechanism used in the preferred embodiment.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0028] Referring now more particularly to the drawings, FIG. 1illustrates a particular embodiment of an electrosurgical lesionlocation device 20 constructed in accordance with the present invention.The lesion location device 20 includes an elongated, tubular trocarportion 22 and a handle portion 24. The proximal end of the trocarportion 22 is fixed to an attachment fitting 26, by which the trocarportion 22 is removably attached to the handle portion 24. A detaileddescription of the trocar portion 22 will be provided first, followed bydescriptions of the attachment fitting 26 and the handle portion 24.

The Trocar Portion

[0029] The trocar portion 22 (hereinafter referred to as the trocar 22)extends between the proximal attachment fitting 26 and a hemisphericaldistal tip 28, the latter preferably being formed of high densitypolyethylene (HDPE) or the like. The trocar 22 is advantageouslyprovided with a cutting element 30 that extends distally from the distaltip 28 of the trocar 22. The cutting element 30 is preferably anelectrosurgical electrode, such as the type disclosed and claimed incommonly-assigned, co-pending U.S. patent application Ser. No.09/159,467 for “Electrosurgical Biopsy Device and Method,” thedisclosure of which is incorporated herein by reference. The cuttingelement or electrode 30 is preferably made of 302 stainless steel wire,of approximately 0.014 in. (approximately 0.36 mm) diameter. Asexplained below, the electrode 30 is activated with radio frequency (RF)electrical energy to ablate adjacent tissue.

[0030] In the preferred embodiment illustrated, the elongate trocar 22comprises a proximal trocar tube 31 and a distal trocar tube 32,connected by an intermediate member 33. The trocar tubes 31, 32 and theintermediate member 33 may be formed of a sturdy, high impactbiocompatible material, such as medical grade polymer (e.g.,polycarbonate). In a particular example of the device, the outsidediameter of the trocar 22 is approximately 0.125 in. (approximately 3.2mm), although this dimension is exemplary only.

[0031] Electrosurgical techniques have been used in a variety ofcircumstances. In electrosurgery, high frequency electrical energy isapplied through a primary electrode to tissue. The electrical energyflows through the tissue to a return electrode. The tissue adjacent tothe primary electrode is ablated, to form an opening in the tissue. Thereturn electrode in monopolar electrosurgery may be an electrode placedon the exterior of the patient's body at a point remote from the primaryelectrode. In bipolar electrosurgery, the return electrode may be asmaller electrode positioned somewhat near the primary electrode. Anexemplary biopsy instrument using electrosurgical techniques isdescribed in International Application Number PCT/US97/15092 (ApplicantEthicon Endo-Surgery), published under the Patent Cooperation Treaty onMar. 5, 1998 with International Publication Number WO 98/08441. Anotherelectrosurgical biopsy instrument is disclosed and claimed inabovementioned U.S. patent application Ser. No. 09/159,467.

[0032] The illustrated embodiment of the present invention usesmonopolar electrosurgical techniques to cut through subcutaneous tissuesto reach a target tissue mass. Electrical energy is provided to theelectrode 30. The return electrode (not shown) is attached to thepatient's body remote from the point at which the trocar 22 is insertedto provide the return electrical path. Alternatively, theelectrosurgical aspect of the device may be bipolar, in which the returnelectrical path is provided by a return electrode (not shown) on thedevice itself. A conductor 34 (FIG. 3) extends axially through theinterior of the trocar portion 22 to conduct electrical energy from thehandle portion 24 of the device to the electrosurgical electrode 30. Theconductor 34 is insulated to maintain electrical isolation from theadjacent components, which may be of conductive metal, as explainedbelow.

[0033] Referring now to FIGS. 3 through 6A, the intermediate member 33of the trocar 22 has a proximal portion 35 that is dimensioned to fitsnugly into the open distal end of the proximal trocar tube 31, and adistal portion 36 that is similarly dimensioned to fit snugly into theopen proximal end of the distal trocar tube 32. The proximal portion 35is provided with a first plurality of longitudinal grooves or channels37 in its outer surface, each of which opens into one of a firstplurality of axially-elongate, slot-like apertures 38 that are formed inthe intermediate member 33 of the trocar 22. The distal portion 36 ofthe intermediate member 33 is formed with a second plurality oflongitudinal grooves or channels 39, each of which opens into one of asecond plurality of axially-elongate, slot-like apertures 40 that arealso formed in the intermediate member 33, distally from the firstplurality 38. The axial locations of the first and second pluralities ofapertures are such that the distal ends of apertures 38 in the firstplurality overlap slightly with the proximal ends of the apertures 40 inthe second plurality. The apertures 38 in the first plurality alternatewith the apertures 40 in the second plurality around the circumferenceof the trocar portion 22. In the illustrated embodiment, there are sixapertures in each of the first and second pluralities, but this numbermay be varied from as few as two to ten or more. The apertures of eachplurality are evenly spaced around the circumference of the trocar.

[0034]FIG. 3 shows a first plurality of locator wires 42 contained in aretracted position within the trocar portion 22. Each of the firstplurality of locator wires 42 is associated with a corresponding one ofthe first plurality of apertures 38. Each of the first wires 42 has aproximal end that is attached to the distal end of a first tubularwire-carrying member 44 that is mounted for axial movement within theinterior of the proximal trocar tube 31. The distal end of each of thefirst plurality of wires 42 is movably journaled in one of the channels37 in the proximal portion 35 of the intermediate member 33. In theirretracted position, the first locator wires 42 are aligned substantiallylongitudinally within the proximal trocar tube 31, and they are fullycontained therein. The first locator wires 42 are movable between theirretracted position, shown in FIG. 3, and a deployed position, shown inFIGS. 10 and 11. In their deployed position, the first locator wires 42extend substantially radially from the intermediate member 33 of thetrocar 22, to define a first locating perimeter 42 (FIG. 10). The firstlocator wires 42 may be tensioned to provide a radius of curvature ofabout 0.295 in. (about 7.5 mm), and, in their deployed position, theyform a first locating perimeter 46 with a defined diameter of about 1.2in. (about 30 mm). This diameter is exemplary only; both small andlarger locating perimeters may be defined by using locator wires ofdifferent lengths. The first wire-carrying member 44 is longitudinallymounted for axial movement within the interior of the proximal trocartube 31, between a first or proximal position, and a second or distalposition. FIG. 3 shows the first wire-carrying member 44 in its proximalposition, corresponding to the retracted position of the first locatorwires 42. As shown in FIG. 4, as the first wire-carrying member 44 movesaxially toward its distal position, it moves the first locator wires 42attached to it through the channels 37 of the proximal portion 35 of theintermediate member 33, and then into and through the slot-shapedapertures 38 in the first plurality of apertures. When the distal endsof the first locator wires 42 encounter the slot-shaped apertures 38,the first locator wires 42 are allowed to move radially with respect tothe trocar 22. Pre-tensioning the first locator wires 42 so that theytend to bend in an outward, radial direction with respect to the trocaraids in assuring that the first locator wires 42 properly exit theintermediate member 31 of the trocar 22 through the first slottedapertures 38.

[0035] Disposed within the distal trocar tube 32 is a second pluralityof locator wires 50. The second locator wires 50 have a retractedposition in which they extend longitudinally within the distal trocartube 32 and are fully contained therein. Each of the second plurality oflocator wires 50 is associated with a corresponding one of the secondplurality of apertures 40. The second locator wires 50 are movablebetween their retracted position, shown in FIG. 3, and a deployedposition, shown in FIGS. 10 and 11. In the deployed position, the secondlocator wires 50 extend substantially radially from the intermediatemember 33 of the trocar 22, to define a second locating perimeter 52.The second wires 50 may also be tensioned to provide a radius ofcurvature of 0.295 inch (7.5 mm). When the second locator wires 50 arein their deployed position, the distal ends of the second locator wires50 define a circle having a diameter of approximately 0.47 in.(approximately 12 mm).

[0036] The distal ends of the second locator wires 50 are attached tothe distal end of a second tubular wire-carrying member 54. The proximalend of each of the second locator wires 50 is movably journaled withinone of the channels 39 in the distal portion 36 of the intermediatemember 33. The second wire-carrying member 54 is longitudinally mountedfor axial movement within the distal trocar tube 32. Specifically, thesecond wire-carrying member 54 is carried co-axially within the hollowinterior of the first wire-carrying member 44, extending distally intothe interior of the distal trocar tube 32, after slidably passingthrough an axial bore in the intermediate member 33.

[0037] The second wire-carrying member 54 is axially movable between adistal position (FIG. 3), corresponding to the retracted position of thesecond locator wires 50, and a proximal position, corresponding to thedeployed position of the second locator wires 50. As shown in FIG. 4, asthe second wire-carrying member 54 moves axially from its distalposition to its proximal position, the second wire-carrying member 54moves the second locator wires 50 through the journaling channels 39 inthe intermediate member 33 and into the second slot-shaped apertures 40.When the distal ends of the second locator wires 50 encountertheslot-shaped apertures 40, the second locator wires 50 begin to moveradially with respect to the trocar. Pretensioning the second locatorwires 50 so that they tend to bend in an outward, radial direction withrespect to the trocar aids in assuring that the second locator wires 50properly exit the trocar through the second slot-shaped apertures 40.

[0038] The proximal portion 35 of the intermediate member 33 provides astop to limit the axial movement of the first wire-carrying member 44 inthe distal direction, away from the handle portion 24 of the device (seeFIG. 1). When the distal end of the first wire-carrying member 44engages the proximal portion 35 of the intermediate member, the firstwire-carrying member 44 is at its distal position, and the first locatorwires 42 are fully deployed.

[0039] In the preferred form, the distal end of the second wire-carryingmember 54 is diametrically enlarged to provide a flared end 56, to whichthe second locator wires 50 are attached. The diameter of the flared end56 is greater than the diameter of the axial bore through theintermediate member 33, so that the distal portion 36 of theintermediate member 33 provides a stop to limit the axial movement ofthe second wire-carrying member 54 in the proximal direction. When thislimit is reached, the second wire-carrying member 54 is at its proximalposition, which corresponds to the second locator wires 50 being fullydeployed.

[0040] Each of the first locating wires 42 and the second locating wires50 corresponds to one of the first apertures 38 and second apertures 40,respectively. In the illustrated embodiment, six first locating wires 42and six second locating wires 50 are uniformly spaced around the trocar.In other embodiments, the number of first locator wires 42 may differfrom the number of second wires 50, and the number of each may vary fromas few as two to ten or more. Furthermore, the locator wires in eachplurality (and especially the first plurality 42) may be of differentlengths to provide locating perimeters of different shapes andconfigurations. For example, the locator wires 42 of the first pluralitymay be dimensioned to provide a hemispherical perimeter to access targettissue masses that are near the patient's chest wall, or they mayprovide an asymmetrical perimeter if the target tissue mass is near thesurface of the patient's skin. Any configuration can be provided when itis desired to avoid piercing an adjacent organ, or penetrating anadjacent cavity.

[0041] When the locating wires 42, 50 that are respectively in the firstand second locator wire pluralities are deployed, their tips define thefirst and second locating perimeters 46, 52, respectively. The curvatureof the first locating wires 42 in the proximal direction and thecurvature of the second locator wires 50 in the distal directionpreferably results in the first and second perimeters 46, 52 beingsubstantially coplanar (defining a plane that is transverse to the axisof the trocar 22). Alternatively, the first perimeter 46 may define aplane that lies a short distance proximally from the plane defined bythe second perimeter 52.

[0042] When the trocar 22 is inserted through a target tissue mass, asguided by mammography, ultrasound, or other techniques, the first andsecond locator wires 42, 50 are deployed. When deployed, the first andsecond locator wires respectively extend into the tissue surrounding atarget tissue mass (such as a suspected lesion or tumor) in axiallyopposite directions, thereby securely anchoring the trocar in thetissue. Accordingly, the trocar is less prone to move within the tissueor to be inadvertently removed therefrom, and thus it provides a moreaccurate guide for subsequent surgery than has previously been possible.Thus, this anchoring action reduces the possibility that the trocar willshift position or become dislodged before the surgeon has theopportunity to perform the appropriate surgery. Furthermore, the firstlocating perimeter 46 may be used to define the periphery of the targettissue mass. Thus, while both pluralities of locator wires are securedwithin the target tissue mass and thus locate and identify it, the firstlocator wires 42 also help identify the outer periphery of the targetmass, with perhaps an added margin of tissue that is identified forremoval with the target tissue mass.

[0043] In their deployed positions, the distal tips of the first locatorwires 42 extend farther from the trocar than the distal tips of thesecond locator wires 50. To provide this capability, the firstwire-carrying member 44 has a range of axial movement that is greaterthan the range of axial movement of the second wire-carrying member 54.Preferably, the range of axial movement of the first wire-carryingmember 44 is about twice the range of axial movement of the secondwire-carrying member 54. The mechanism that provides these respectiveranges of movement is described below in the description of the handleportion of the invention.

[0044] Furthermore, the first and second locator wires 42, 50 areelectrically energized to provide monopolar electrosurgical tissuepenetration with minimal deployment force. Optionally, the continuedelectrical energization of the locator wires after deployment may resultin tissue desiccation that facilitates the visualization of the targettissue mass by means of color and/or texture differentiation fromsurrounding tissue. In this embodiment, the first and/or second locatingwires may be electrically connected to a source (not shown) ofelectrical energy to provide for electrosurgical penetration. For thispurpose, the first and second locating wires 42, 50 may be about 0.009in. (0.23 mm) in diameter, and are advantageously formed of 17-7stainless steel or an equivalent. The wires may be coated (except fortheir distal ends) with a polymer having a high dielectric strength, sothat the tip of each locating wire 42, 50 is the only part of the wirethat is energized at the time the wires are deployed from the trocar. Insuch an embodiment, the first and second wire-carrying elements 44, 54are made of electrically conductive metal tubing to provide anelectrical path along the trocar from the handle portion 24 (FIG. 1) tothe locator wires 42, 50. For example, the first and secondwire-carrying members 44, 54 may be formed of stainless steel.

[0045] Proximal and distal guide marks 57 a, 57 b may advantageously beprovided on the outer surface of the trocar 22. The proximal mark 57 ais spaced a small distance proximally from the first apertures 38, whilethe distal mark 57 b is spaced a small distance distally from the secondapertures 40. The distance between the marks 57 a, 57 b is preferablyapproximately equal to the diameter of the first locator wire perimeter46, thereby defining in the axial direction a perimeter that issubstantially equal to the first perimeter 46 defined by the firstlocator wires 42. The marks 57 a, 57 b may be made with a material thatis easily visible to the surgeon or that is readily detected in themammography, x-ray, ultrasound, or other radiological examination.Alternatively, they can be illuminated via fiber optic means (notshown).

[0046] It may be advantageous to modify the one or more of the first orsecond locating wires 42, 50 for better visualization. For example, asshown in FIG. 14, a locator wire 42′ may be formed with a hollowinterior and contain an optical fiber 43 that extends out of an open endof the wire. This allows the tip of the locating wire to be illuminatedfor easier visualization of the target tissue mass and the surroundingtissue as a guide during surgery. Alternatively, or in addition, one ormore of the first or second locator wires 42, 50 may be formed as anopen-ended hollow wire 42″, as shown in FIG. 15, to provide a passage 47for the injection of a dye into the local region of tissue, to assist inguiding the surgeon in the subsequent surgery.

The Attachment Fitting

[0047] The attachment fitting 26 is best shown in FIG. 13. It comprisesa narrow, elongate housing 58 having a distal end fixed to the proximalend of the proximal trocar tube 31, and a proximal end formed into a lip59. A transverse finger 60, the purpose of which will be describedbelow, extends laterally from the housing 58 near its distal end. Thehousing 58 includes a pair of opposed side walls 61 that define achannel 63. The first and second wire-carrying members 44, 54, extendinto the channel 63 through an opening (not shown) at the distal end ofthe housing 58. The first wire-carrying member 44 has a proximal end towhich is fixed a first attachment lug 62. The second wire-carryingmember 54 has a proximal end, extending outwardly from the open proximalend of the first wire-carrying member 44, to which is fixed a secondattachment lug 64. The attachment lugs 62, 64 extend out of the channelopening defined by the ends of the side walls 61.

[0048] The proximal end of the housing 58 is provided with first andsecond electrical contacts 66 a, 66 b. The first contact 66 a iselectrically connected to the central conductor 34 that extendsproximally out of the proximal end of the second wire-carrying member54. The second contact 66 b is electrically connected by a coiled wireto the second wire-carrying member 54. The first and secondwire-carrying members 44, 54 are formed of an electrically conductivemetal, and the second wire carrying member 54 is contained coaxiallywithin the first wire carrying member 44, establishing physical contactbetween the two wire-carrying members 44, 54. Thus, an electrical pathis established from the second wire carrying member 54 to the firstwire-carrying member 44.

The Handle Portion

[0049] The handle portion 24 is described with reference to FIGS. 1, 7,8, 9, 12, 16, and 17. As best shown in FIG. 1, the handle portion 24 hasan outer housing 70 that is dimensioned and configured to be heldcomfortably by the radiologist or surgeon operating the device, whilebeing large enough to enclose the internal electrical and mechanicalcomponents that will be described below. The housing 70 isadvantageously formed of a rigid, nonconductive polymer material.

[0050] The housing 70 includes a longitudinal slot 72 configured anddimensioned for receiving the attachment fitting 26. The transversefinger 60 of the attachment fitting 26 fits into a short transverse slot73 (FIG. 12) that branches off the longitudinal slot 72 near its distalend. A latch 74 (best shown in FIGS. 8 and 9) extends across thetransverse slot 73 to engage the finger 60. When the finger 60 is in thetransverse slot 73 and the latch 74 engages the finger 60, the latch 74holds the attachment fitting 26 in the longitudinal slot 72. The slot 72has an opening 75 (FIG. 12) at its proximal end that receives the lip 59at the proximal end of the attachment fitting 26, thereby releasablysecuring the proximal end of the fitting 26 in the slot 72. A spring 77(FIGS. 8 and 9) biases the latch 74 in place across the transverse slot73. A thumb release 76 attached to the latch 74 permits the user toovercome the bias force of the spring 75 to release the latch 74,freeing the finger 60, and thereby permitting the removal of the trocar22 and the attachment fitting 26 from the handle 24. The thumb release76 is arranged to permit one-handed release of the trocar portion 22from the handle portion 24 by a person holding the handle portion 24.

[0051] First and second electrical contacts 80, 81 in the longitudinalslot 72 (FIG. 12) provide electrical connections between the handleportion 24 and the first and second contacts 66 a, 66 b, respectively,in the attachment fitting 26. As described above, the first and secondwire-carrying members 44, 54 may be electrically conductive to providesuch electrical connectivity to the locator wires 42, 50. The attachmentfitting 26 is configured so that when it is inserted into the elongateslot 72 of the handle portion 24, appropriate electrical contact is madebetween the handle portion contacts 80, 81 and the attachment fittingcontacts 66 a, 66 b, respectively. For example, the trocar conductor 34leading to the electrosurgical electrode 30 may make electrical contactwith the first handle contact 80 through the first attachment fittingcontact 66 a, and the first and second wire-carrying members 44, 54 maymake electrical contact with the second handle contact 81 through thesecond attachment fitting contact 66 b.

[0052] Electrical energy is provided to the handle electrical contacts80, 81 from a power cord 82 (FIG. 1). Power may be supplied to the powercord 82 by any suitable, commercially-available electrosurgicalgenerator (not shown), preferably one that generates an output signalhaving a frequency of about 0.5 MHz to about 1 MHz. Such generatorstypically have a foot-pedal operated power switch (not shown) forturning the electrical power to the handle on and off.

[0053] A control lever 83 on the handle portion 24 allows the surgeonselectively to energize the electrosurgical electrode 30 and the locatorwires 42, 50. The control lever 83 is preferably placed on one side ofthe handle portion 24 so that the surgeon can manipulate the controllever 83 with a thumb or finger of the same hand the surgeon is using tohold the handle portion 24.

[0054] The control lever 83 preferably has two positions: a firstposition in which electrical energy is provided to the first handlecontact 80 for providing electrical energy to the electrosurgicalelectrode 30; and a second position in which electrical energy isprovided to the second handle contact 81 for energizing the locatorwires 42, 50. Specifically referring to FIGS. 16 and 17, the controllever 83 is mounted on a shaft 84 that extends into the housing 70.Mounted on the shaft 84 within the housing is a switch actuator 85 thatrotates with the shaft 84. The switch actuator 85 is connected to oneend of an elongate, flexible conductive switching element 86, the otherend of which is connected to a terminal 87, which, in turn, iselectrically connected to wires from the power cord 82. First and secondswitch contacts 88 a, 88 b are provided in the housing, the firstcontact 88 a being connected by a first wire conductor 89 a to the firsthousing contact 80, and the second contact 88 b being connected by asecond wire conductor 89 b to the second housing contact 81. The switchactuator has a first position (FIG. 16), corresponding to the firstposition of the control lever 83, in which the switch element 86 isbrought into contact with the first switch contact 88 a, and a secondposition (FIG. 17), corresponding to the second position of the controllever 83, in which the switch element 86 is brought into contact withthe second switch contact 88 b.

[0055] Means (not shown) may optionally be included to provide differentpower levels to the handle contacts 80, 81. For example, when the switchactuator 85 is in the first position, power between 60 and 104 watts at1 MHz may be supplied to the first handle electrical contact 80. Whenthe switch actuator 85 is in the second position, power between 43 and55 watts at 1 MHz may be supplied to the second handle electricalcontact 81. The electronic circuitry to provide these dual power levelsis considered to be well within the level of ordinary skill in thepertinent arts.

[0056] The handle portion 24 includes a deployment mechanism 90 (seeFIGS. 8 and 9) to control movement of the first and second tubularelements 44, 54 of the trocar for deploying the first and second locatorwires 42, 50 (see FIGS. 3 and 4). The deployment mechanism 90 includes afirst, proximal slider 92, and a second, distal slider 94. As will beapparent from the following description, the first, proximal slider 92controls the movement of the first tubular element 44 for deploying thefirst locator wires 42. The second, distal slider 94 controls themovement of the second tubular element 54 for deploying the secondlocator wires 50.

[0057] In the embodiment illustrated, the deployment mechanism 90 movesthe first and second sliders 92, 94 simultaneously in oppositedirections. The simultaneous movement of the first and second sliders92, 94 simultaneously moves the first and second wire-carrying members44, 54, thereby also simultaneously deploying the first and secondlocator wires 42, 50. A connecting element 96 links the first slider 92and the second slider 94. The connecting element 96 includes an elongatebody that has a first end slot 102 and a second end slot 104. The firstend slot 102 engages a pin 103 on the first, proximal slider 92. Thesecond end slot 104 engages a pin 105 on the second, distal slider 94.The connecting element 96 is pivotally secured to the body of the handleportion 24 at a pivot point 108.

[0058] As noted above, the range of axial movement within the trocar ofthe first wire-carrying member 44 that deploys the first locator wires42 is approximately twice the range of axial movement of the secondwire-carrying member 54 that deploys the second locator wires 50. Thedeployment mechanism 90, and particularly the connection 96 between thefirst slider 92 and the second slider 94, provides a greater range ofmovement for the first slider 92 than the second slider 94. The pivotpoint 108 is positioned along the body of the connecting element 96 sothat the first end of the connecting element 96 (with the first slot102) has a longer range of movement than the second end of theconnecting element 96 (with the second slot 104). The configurationcauses the second slider to move about one half the distance the firstslider moves. The first end slot 102 is approximately twice the lengthof the second to end slot 104 to accommodate this different range ofmovement.

[0059] The connection between each slider 92, 94 and its respectivecorresponding wire-carrying member 44, 54 is provided by a transverseextension 110, 112 at the distal end of each slider 92, 94 ,respectively. As best shown in FIG. 12, the extension 110 of the firstslider 92 has an aperture 111, and the extension 112 of the secondslider 94 has an aperture 113. As shown in FIG. 7, the aperture 111 onthe first slider 92 receives the attachment lug 62 on the firstwire-carrying member 44, and the aperture 113 on the second slider 94receives the attachment lug 64 of the second wire-carrying member 54.

[0060] A thumb control 98 positioned on the top side of the handleportion 24 is directly attached to the first, proximal slider 92.Specifically, the thumb control 98 includes a pin 114 that rides in aslot 116 in the top of the handle housing 70 (FIG. 1). The pin 114extends into the interior of the housing 70 and is received in a recess118 in the first slider 92, as shown in FIGS. 8 and 9. As the thumbcontrol 98 is moved longitudinally in the slot 116 from a proximalposition (shown in FIG. 8) to a distal position (shown in FIG. 9) thethumb control 98 moves the first slider 92 longitudinally from itsproximal position toward its distal position. When the attachmentfitting 26 is installed in the handle portion 24, the first slider 92 isdirectly connected to the first tubular member 44, so the movement ofthe first slider 92 toward its distal position moves the first tubularmember 44 toward its distal position, deploying the first locator wires42. As the first slider 92 is moving from its proximal position to itsdistal position, the connecting element 96 connecting the first andsecond sliders 92, 94 causes the second slider 94 to simultaneously movefrom its distal position toward its proximal position, though at a rateless than (on the order of one-half) the rate of movement of the firstslider 92. The second slider 94 is connected to the second tubularmember 54, so that the movement of the second slider 94 directlycorresponds to the movement of the second tubular member 54. Therefore,the movement of the second slider 94 from its distal position to itsproximal position moves the second tubular member 54 from its distalposition (in which the second locator wires 50 are retracted) toward itsproximal position (in which the second locator wires are deployed).

[0061] It may be advantageous to provide a lock-out mechanism betweenthe control lever 83 and the locator wire deployment mechanism 90,whereby deployment of the locator wires 42, 50 is prevented when thelever 83 is positioned for energizing the electrode 30. An exemplarylock-out mechanism is shown in FIGS. 16 and 17. As shown, the switchactuator 85 is formed with a lobe or finger 120 having a notch 122. Whenthe switch actuator 85 in the first position (in which the cuttingelement 30 is energized, as described above), the notch 122 engages adetent 124 at the proximal end of the first slider 92. This engagementlocks the first slider 92 in its proximal position, thereby blocking themovement of both sliders 92, 94 due to their linkage by the linkingelement 96. With both sliders 92, 94 inhibited from movement, deploymentof the locator wires 42, 50 is prevented. When deployment of the locatorwires 42, 50 is desired, the switch actuator 85 is rotated by thecontrol lever 83 to its second position (FIG. 17), releasing the detent124 from the notch 122, and thereby unlocking the sliders 92, 94.

Operation

[0062] In operation, a target tissue mass is identified throughconventional visualization means, as described above. A small, shallowincision is then made (e.g., by a scalpel) at an appropriate place onthe patient's body to provide an entry site for the trocar 22. Tooperate the electrosurgical lesion location device 20 to localize andmark target tissue mass, a surgeon places the control lever 83 its firstposition to supply electrical energy to the electrosurgical electrode30. The distal tip 28 of the trocar 22 is inserted into the incision andinto the subcutaneous tissue. The energized cutting electrode 30 cutsinto the tissue until the distal trocar tip 28 extends through thetarget tissue mass and the intermediate portion 33 is located within thetarget tissue mass, as indicated by mammography or other visualizationmeans.

[0063] Once the trocar 22 is in place in the tissue, the surgeon movesthe control lever 83 to its second position to activate theelectrosurgical tips of the first and second locator wires 42, 50. Thesurgeon slides the thumb control 98 from its proximal position to itsdistal position. As described above, this movement of the thumb control98 deploys the first and second locator wires 42, 50 into the tissue, toanchor the trocar 22 in place, and identify the tissue to be removed insubsequent surgery. Preferably, the trocar 22 is positioned so that thelocator wires 42, 50 extend to the periphery of the tissue to beremoved, as described above. Once the trocar 22 has been inserted, andanchored with the locator wires 42, 50, the flow of electrical energy tothe trocar 22 is turned off by use of the foot pedal switch of thegenerator (as described above). The thumb release 76 is manipulated torelease the finger 60 of the attachment fitting housing 58, allowing thetrocar 22 to be removed from the handle 24.

[0064] The patient can then be removed to the surgical operating room,with the trocar portion 22 remaining in place, for the surgeon toperform the appropriate surgery. The trocar portion 22 is unlikely toshift position in the tissue as the patient is removed because thelocator wires 42, 50 assist in holding the trocar in position. This istrue even when the tissue is removed from a compressed condition on amammography apparatus. When the surgeon opens the tissue region, thetrocar and the deployed locator wires 42, 50 provide the surgeon directindication of the area of tissue to be removed or otherwise operatedupon.

[0065] Those skilled in the art will recognize that variousmodifications may be made to the specific embodiment illustrated abovewithout departing from the spirit of the present invention. For example,numerous modifications may be made to the handle portion of the device,the mechanism for attaching the proximal end of the trocar to the handleportion of the device, and to the specific mechanism for deploying thelocator wires. In addition, while the preferred embodiment employs anelectrosurgical electrode 30 as the incision-making element, anon-electrical cutting element may work satisfactorily in someapplications. Furthermore, although the preferred embodiment describedabove employs two pluralities of locator wires working in opposition(that is, they are deployed in radially-opposite directions), a deviceemploying only a single plurality of locator wires may be suitable incertain procedures. Moreover, although the preferred embodimentdescribed above employs first and second pluralities of locator wiresthat are deployed simultaneously (in unison), it may be acceptable todeploy the first and second pluralities of locator wires sequentially.These and other modifications that may suggest themselves are consideredto be within the spirit and scope of the invention, as defined in theclaims that follow.

What is claimed is:
 1. A device for localizing a target tissue mass inthe body of a patient, comprising: an elongate, hollow, tubular trocarportion having a proximal end portion and a distal end; and a pluralityof locator wires disposed in the trocar portion and movable between aretracted position in which they are fully contained within the trocarportion, and a deployed position in which they extend radially from thetrocar portion.
 2. The device of claim 1, further comprising anelectrosurgical tissue cutting element at the distal end of the trocarportion.
 3. The device of claim 1, wherein the plurality of locatorwires is a first plurality, and wherein the device further comprises asecond plurality of locator wires disposed in the trocar portion andmovable between a retracted position in which they are fully containedwithin the trocar portion and a deployed position in which they extendradially from the trocar portion.
 4. The device of claim 3, wherein thefirst and second plurality of locator wires respectively define firstand second perimeters when they are in their respective deployedpositions.
 5. The device of claim 1, wherein the trocar portion includesa plurality of circumferentially-spaced apertures through which thelocator wires extend when they are in their deployed position.
 6. Thedevice of claim 5, wherein the locator wires are attached to awire-carrying member disposed axially within the trocar portion forlongitudinal movement between a first position and a second position,and wherein the first position of the wire-carrying member correspondsto the retracted position of the locator wires, and the second positionof the wire-carrying member corresponds to the deployed position of thelocator wires.
 7. The device of claim 4, wherein the trocar portionincludes first and second pluralities of circumferentially-spacedapertures through which the first and second pluralities of locatorwires respectively extend when they are in their deployed positions. 8.The device of claim 7, wherein the first and second pluralities oflocator wires are respectively attached to first and secondwire-carrying members disposed axially within the trocar portion forlongitudinal movement between respective first positions and secondpositions, and wherein the first positions of the wire-carrying memberscorrespond to the retracted positions of the locator wires, and thesecond positions of the wire-carrying members correspond to the deployedpositions of the locator wires.
 9. The device of claim 8, wherein thefirst wire-carrying member comprises a first, hollow elongate elementdisposed axially within the trocar portion and having a distal end towhich the first plurality of locator wires are attached, and wherein thesecond wire-carrying member comprises a second elongate element disposedaxially within the first elongate element and having a distal end towhich the second plurality of locator wires are attached.
 10. The deviceof claim 9, wherein the first and second wire-carrying members aremovable in axially opposite directions to each other when they arerespectively moved from their respective first positions to theirrespective second positions and from their respective second positionsto their respective first positions.
 11. The device of claim 8, furthercomprising: a handle portion; an attachment fitting fixed to theproximate end portion of the trocar, wherein the first and secondwire-carrying members extend into the attachment fitting, and whereinthe attachment fitting is removably attachable to the handle portion;and a deployment mechanism in the handle portion and engageable with thefirst and second wire-carrying members when the attachment fitting isattached to the handle portion to move the first and secondwire-carrying members between their respective first and secondpositions.
 12. The device of claim 11, wherein the first position of thefirst wire carrying member and the second position of the secondwire-carrying members are proximal positions and the second position ofthe first wire carrying member and the first position of the secondwire-carrying member are distal positions, and wherein the deploymentmechanism comprises: a first slider engageable with the firstwire-carrying member and movable between a proximal position and adistal position; a second slider engageable with the secondwire-carrying member and movable between a proximal position and adistal position; a linking element connecting the first slider to thesecond slider so that the second slider moves proximally when the firstslider moves distally and the second slider moves distally when thefirst slider moves proximally; and an actuation element engageable withone of the first and second sliders for moving the one of the slidersbetween the proximal and distal positions.
 13. The device of claim 1,wherein the locator wires are formed of a conductive metal, the devicefurther comprising means for connecting the locator wires to a source ofelectrical energy for providing an electrosurgical effect when thelocator wires are in their deployed position.
 14. The device of claim 3,wherein the locator wires in at least one of the first and secondpluralities of locator wires are formed of a conductive metal, thedevice further comprising means for connecting the locator wires in theat least one plurality to a source of electrical energy for providing anelectrosurgical effect when the locator wires in the at least oneplurality are in their deployed position.
 15. A method of localizing andmarking an identified target tissue mass in the body of a patient,comprising the steps of: (a) visualizing the target tissue mass; (b)providing a trocar having a distal end and containing a plurality oflocator wires disposed in the trocar section and movable between aretracted position in which they are fully contained within the trocarportion, and a deployed position in which they extend radially from anintermediate portion of the trocar; (c) during the visualizing step, andwhile the locator wires are in their retracted position, inserting thetrocar into the body so that the distal end passes through the targetmass and so that the intermediate portion of the trocar is within thetarget tissue mass; and (d) moving the locator wires from theirretracted position to their deployed position so that at least some ofthe locator wires are anchored within the target tissue mass.
 16. Themethod of claim 15, wherein the step of inserting is at least partiallyperformed electrosurgically.
 17. The method of claim 15, furthercomprising the step of electrically energizing at least some of thelocator wires as they are moved to their deployed position.
 18. Themethod of claim 17, wherein the step of electrically energizing iscontinued after the energized locator wires are in their deployedposition to dessicate tissue in the proximity of the energized locatorwires.
 19. The method of claim 15, wherein the trocar contains first andsecond pluralities of locator wires that are movable in unison fromrespective retracted positions fully contained within the trocar tofirst and second respective deployed positions radially extending fromthe intermediate portion of the trocar, the deployed position of thelocator wires in the first and second pluralities respectively definingfirst and second perimeters, and wherein the moving step comprises thestep of moving the locator wires in the first and second pluralitiesfrom their respective retracted positions to their respective deployedpositions, whereby at least some of the locator wires in the firstplurality are anchored in the target tissue mass and at least some ofthe locator wires in the second plurality are anchored in tissuesurrounding the target tissue mass.
 20. Apparatus for localizing atarget tissue mass in the body of a patient, comprising: an elongatetrocar portion having a proximal end and a distal end; a cutting elementat the distal end of the elongate trocar; a handle portion; anattachment fitting attached to the proximal end of the trocar portionand configured for removable attachment to the handle portion; and atleast a first plurality of locator wires that are movable between aretracted position within the trocar portion, and a deployed positionextending substantially radially from the trocar portion.
 21. Theapparatus of claim 20, wherein the cutting element is an electrosurgicalcutting element.
 22. The apparatus of claim 20, wherein the locatorwires of the first plurality of locator wires are connected to a firstelongate member longitudinally mounted for axial movement within thetrocar portion between a proximal position corresponding to theretracted position of the first plurality of locator wires, and a distalposition corresponding to the deployed position of the first pluralityof locator wires.
 23. The apparatus of claim 20, further comprising asecond plurality of locator wires that are movable between a retractedposition within the trocar portion, and a deployed position extendingsubstantially radially from the trocar portion.
 24. The apparatus ofclaim 23, wherein when in their respective deployed positions, the firstand second pluralities of locator wires respectively define first andsecond locating perimeters.
 25. The apparatus of claim 23, wherein thecutting element is an electrosurgical cutting element and at least someof the first and second plurality of locator wires are electrosurgicalelectrodes.
 26. The apparatus of claim 23, wherein: the first pluralityof locator wires is connected to a first tubular member longitudinallymounted for axial movement within the trocar portion between a proximalposition corresponding to the retracted position of the first pluralityof locator wires, and a distal position corresponding to the deployedposition of the first plurality of locator wires; and the secondplurality of locator wires is connected to a second tubular memberlongitudinally mounted for axial movement within the trocar portionbetween a distal position corresponding to the retracted position of thesecond plurality of locator wires, and a proximal position correspondingto the deployed position of the second plurality of locator wires. 27.The apparatus of claim 26, wherein the trocar portion includes first andsecond pluralities of slot-shaped apertures through which the first andsecond pluralities of locator wires respectively emerge when moved totheir respective deployed positions.
 28. The apparatus of claim 20,wherein at least one of the locator wires is a hollow wire.
 29. Theapparatus of claim 20, wherein at least one of the locator wirescontains an optical fiber.
 30. The apparatus of claim 20, wherein, whenin their retracted position, the locator wires of the at least firstplurality of locator wires are aligned substantially longitudinallywithin the trocar portion.
 31. Apparatus for localizing a target tissuemass in the body of a patient, comprising: a tubular trocar portionhaving a proximal end and a distal end; an electrosurgical cuttingelement at the distal end of the trocar portion; a first wire-carryingmember longitudinally mounted for axial movement within the trocarportion between a proximal position and a distal position; a secondwire-carrying member longitudinally mounted for axial movement withinthe trocar portion between a proximal position and a distal position; afirst plurality of locator wires attached to the first wire-carryingmember, wherein the first plurality of locator wires are in a retractedposition contained within the trocar portion when the firstwire-carrying member is in its proximal position, and in a deployedposition extending substantially radially from the trocar portion whenthe first wire-carrying member is in its distal position; a secondplurality of locator wires attached to the second wire-carrying member,wherein the second plurality of locator wires are in a retractedposition contained within the trocar portion when the secondwire-carrying member is in its distal position, and in a deployedposition extending substantially radially from the trocar portion whenthe second wire-carrying member is in its proximal position; adeployment mechanism for moving the first wire-carrying member from itsproximal position to its distal position and the second wire-carryingmember from its distal position to its proximal position; and first andsecond pluralities of apertures in the trocar portion, corresponding tothe first and second pluralities of locator wires, and through which thefirst and second pluralities of locator wires emerge from the trocarportion when they are moved from their respective retracted positions totheir respective deployed positions.
 32. The apparatus of claim 31,wherein: at least some of the locator wires of the first and secondplurality of locator wires are electrosurgical electrodes.
 33. Theapparatus of claim 32, wherein the first and second wire-carryingmembers are electrically conductive.
 34. The apparatus of claim 31,wherein the first wire-carrying member comprises a hollow tubularmember, and wherein the second wire-carrying member comprises a secondtubular member carried coaxially within the first tubular member. 35.The apparatus of claim 31, wherein the deployment mechanism comprises: afirst slider engageable with the first wire-carrying member and movablebetween a proximal position and a distal position; a second sliderengageable with the second wire-carrying member and movable between aproximal position and a distal position; a linking element connectingthe first slider to the second slider so that the second slider movesproximally when the first slider moves distally and the second slidermoves distally when the first slider moves proximally; and an actuationelement engageable with one of the first and second sliders for movingthe one of the sliders between the proximal and distal positions. 36.The apparatus of claim 31, wherein at least some of the first and secondpluralities of wires are hollow.
 37. The apparatus of claim 31, whereinat least some of the first and second pluralities of wires contain anoptical fiber.
 38. The apparatus of claim 31, further comprising:switching means having a first position in which electrical power isprovided to the cutting element; and a lock-out mechanism, operablebetween the switching means and the deployment mechanism, for blockingthe movement of the first and second wire-carrying members when theswitching means is in its first position.
 39. A method of localizing anidentified target tissue mass in the body of a patient, the methodcomprising the steps of: (a) providing an elongate, tubular trocarhaving a distal end a proximal end portion, the trocar containing withinit a plurality of locator wires that are deployable from the proximalend portion so as to extend substantially radially from the trocar; (b)inserting the trocar into the body so that its distal end passes throughthe target tissue mass; and (c) deploying the locator wiressubstantially radially from the trocar so that the locator wires extendinto the target tissue mass.
 40. The method of claim 39, wherein thetrocar contains within it first and second pluralities of locator wiresthat are deployable from the proximal end portion so as to extendradially from the trocar to respectively define first and secondlocating perimeters, and wherein the deploying step comprises the stepof simultaneously deploying the first and second pluralities of locatorwires substantially radially from the trocar, so that the first andsecond pluralities of locator wires respectively define the first andsecond locating perimeters.
 41. The method of claim 39, wherein the stepof inserting the trocar comprises the step of electrosurgically cuttingthrough the target tissue mass.
 42. The method of claim 41, wherein thestep of deploying the locator wires includes the step ofelectrosurgically inserting the locator wires into the target tissuemass.
 43. The method of claim 39, wherein at least some of the locatorwires are hollow wires, and wherein the method further comprises thestep of: (d) during or after the deploying step, injecting a dye throughthe hollow wires.
 44. The method of claim 42, wherein, following thestep of deploying, the method further comprises the step of: (d)desiccating tissue adjacent the deployed locator wires by supplying thelocator wires with electrical energy.